In my country there are phone plans where you specify few phone numbers (usually your wife or children) and have very low tariffs for calling those numbers.

To be sure, there are numbers that are toll free and the receiving party is charged for calling, much like the arrangement that Indian telecoms are proposing to get into with e-com sites like Flipkart. Toll-free numbers can be seen as incentives to call a particular number more than others. Aren't they violating the "Telephony Neutrality" principle ?

Yes, I am aware of toll free numbers and the like. The phone number analogy is not quite suitable as a counterargument against internet.org, but it was not meant to be one either. It was more a conter to the devil's advocate line of questions.

The tariff and regulatory structure of telephony is different from internet access. "Telephony Neutrality" basically says that you can call anybody you like as long as you can afford it and you are free to receive phone calls from anybody.

Internet.org is thus more like: "you can call these toll free numbers, but you cannot receive calls from anybody we haven't preapproved".

they do, long distance are charged differently then local and same network calls, and 1800 reverse the paying party. 100, 101, 191 are free. 5* sms cost extra. You can get a plan which frees few nos. or get unlimited call to 1 no.

I addressed these issues in a sibling comment, but the main gist of the argument is that in telephony within tarrif groups there is no discrimination between different numbers.

There is nothing magical about the IP address of internet.org that makes packets to and from it special. Hence zerorating should be applied to either all IP addresses or none.